Heat exchanger

ABSTRACT

A heat exchanger comprising: a corrugated plate; a base plate;  
     a cover plate; a plurality of flow paths A and a plurality of flow pats B defined by the corrugated plate, the base plate and the cover plate disposed so as to interpose said corrugated plate therebetween; and  
     the plurality of flow paths A and the plurality of flow paths B being alternately and adjacently arranged on both sides of the corrugated plate for exchanging heat between fluid A and fluid B via the corrugated plate by supplying fluid A through a plurality of flow paths A and fluid B through a plurality of flow paths B,  
     wherein at least one of end portions of the plurality of flow paths is hermetically sealed by making partial cuts at the end portions of the corrugated plate and/or folding a part of the end portions of the corrugated plate, bending opposing ends of the corrugated plate so as to form respectively into a se of a gable roof, bringing at least a part of the ends of the corrugated plate into contact with each other, and brazing portions in contact, so that openings of one of the flow paths A and the flow paths B are hermetically sealed for allowing only one of the fluids to flow in/out at each end of the corrugated plate.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a heat exchanger easy tomanufacture and resistant to fluid leakage with low fluid pressurelosses.

[0003] 2. Description of the Related Art

[0004] Referring to FIG. 10 and FIGS. 11A to 11C, one example of theconventional heat exchanger will be describes FIG. 11A to FIG. 11Cillustrate principal members of a heat exchanger divided into piecesrespectively. FIG. 11A shows a base plate 52 to be joined on one of thesurfaces of a corrugated plate 51. FIG. 11B shows a corrugated plate 51.FIG. 11C shows a cover plate 54 to be joined on the other surface of thecorrugated plate.

[0005] In FIG. 10, a heat exchanger manufactured by joining membersshown in FIG. 11A to FIG. 11C is illustrated. Referring first to FIG.11A to FIG. 11C, the description will be made. A plurality of flow paths53 are formed by joining a base plate 52 on one of the surfaces of thecorrugated plate 51. A plurality of flow paths 56 are formed by joininga body portion 55 of the cover plate 54 on the other surface of thecorrugated plate 51. The base plate 52 and the sleeve portion 57 of thecover plate 54 are joined and outlet ports 58, 59 for fluid A and fluidB are formed on the upper portion of the base plate 52 and on the lowerportion of the body portion 55 of the cover plate respectively.

[0006] Referring now to FIG. 10, the openings at the lower end of theheat exchanger surrounded by the base plate 52 and the cover plate 54are inlet ports 61 for fluid A, and the inlet ports 61 are provided withhollow bodies (not shown) extending in the same direction as the lengthof the respective flow paths 53, 56 for supplying fluid A. The openingsat the upper end are inlet ports 62 for fluid B, and the inlet ports 62are provided with hollow bodies (not shown) extending in the samedirection as the length of the respective flow paths 53, 56 forsupplying fluid B. The upper end portions of the flow paths 53 and thelower end portions of the flow paths 56 are plugged up with sealingmaterial 60 and hermetically sealed.

[0007] In this conventional heat exchanger, heat exchange between fluidA and fluid B is performed through the corrugated plate by supplyingfluid A and fluid B into the respective flow paths 53, 56 through therespective cylindrical bodies and the respective inlet ports 61, 62, anddischarging out through the outlet ports 58, 59 of the respective flowpaths 53, 56.

[0008] In the conventional heat exchanger, the cad portions of thecorrugated plate in the vicinity of the inlet ports for fluid areplugged up with sealing material or the like and hermetically sealed.However, since the corrugated plate is thin-walled and the area to behermetically sealed is large, the sealing operation needs much time andefforts, and defective hermeticity is apt to occur, whereby fluid may beleaked from the flow paths A to the flow paths B, or from the flow pathsB to the flow paths A,

[0009] As a measure for improving hermeticity, a method of crushing theend portions of the corrugated plate to be sealed is conceivable.However, complete hermeticity cannot be expected simply by the crashingoperation. As shown in FIG. 10, joints between the corrugated plate 51and the base plate 52, and between the corrugated plate 51 and the coverplate 54 are also seated hermetically by the use of adhesive agent orsealing material. However, such sealing operation also needs much timeand effort, and defective hermeticity is apt to occur, whereby fluid maybe leaked as in the end portions of the corrugated plate.

[0010] In addition, fluid supplied through the hollow body impinges onthe filler plugged at the end portion of the corrugated plate at theposition where the flowing area decease at the inlet port, and then thedirection of the flow of fluid is bent at a right angle internallythereof. As a consequent, excessively turbulent flow of fluid occursinternally thereof, and pressure losses increase, thereby making largethe size of the fin and resulting in steep-rise of electricity expense.

[0011] By the way, the fluid pressure losses Δp in the entire heatexchanger are a value obtained by subtracting pressure increase Δp_(out)due to increase in the area at the fluid outlet from the sum of pressurelosses Δ p_(in) due to decrease in the area at the inlet ports of theheat exchanger and a change in flowing direction and pressure lossesΔP_(core) at the time when fluid flows through flow paths. SinceΔP_(core) and ΔP_(out) among the above are determined by thespecification of design, decrease in pressure losses ΔP depends on howmuch ΔP_(in) can be decreased.

SUMMARY OF THE INVENTION

[0012] In order to solve the problems described above, the firstembodiment of the invention is a heat exchanger comprising: a corrugatedplate; a base plate; a cover plate; a plurality of flow paths A and aplurality of flow paths B defined by said corrugated plate, said baseplate and said cover plate disposed so as to interpose said corrugatedplate therebetween; and said plurality of flow paths A and saidplurality of flow paths B being alternately and adjacently arranged onboth sides of the corrugated plate for exchanging heat between fluid Aand fluid B via the corrugated plate by supplying fluid A through aplurality of flow paths A and fluid B through a plurality of flow pathsB, wherein at least one of end portions of the plurality of flow pathsis hermetically sealed by making partial cuts at the end portions of thecorrugated plate and/or folding a part of the end portions of thecorrugated plate, bending opposing ends of the corrugated plate so as toform respectively into a shape of a gable roof, bringing at least a partof the ends of the corrugated plate into contact wit each other, andbrazing portions in contact, so tat openings of one of the flow paths Aand the flow paths B are hermetically sealed for allowing only one ofthe fluids to flow in/out at each end of the corrugated plate.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 is a perspective view showing a heat exchanger according tothe first embodiment of the invention;

[0014]FIG. 2A to FIG. 2C are explanatory drawings showing a way ofhermetically sealing the end portions of the corrugated plate in thebeat exchanger according to the invention;

[0015]FIG. 3 is m explanatory drawing showing another way ofhermetically sealing the end of the corrugated plate of the heatexchanger according to the invention;

[0016]FIG. 4 is a perspective view of a heat exchanger according to thesecond embodiment of the invention;

[0017]FIG. 5A to FIG. 5C are explanatory drawings showing furtheranother way of hermetically sealing the end portions of the corrugatedplate in the heat exchanger according to an embodiment of the invention;

[0018]FIG. 6A to FIG. 6D are explanatory drawings showing Further way ofhermetically sealing the end portions of the corrugated plate in theheat exchanger according to the invention;

[0019]FIG. 7A to FIG. 7C are examples 1 to 3 of the invention, FIG. 7Dand FIG. 7E are partial plan views showing an upper end portions of theflow paths A of the comparative examples 1 and 2, respectively;

[0020]FIG. 8 is an explanatory drawing showing a way of inspecting thehermeticity of the heat exchanger;

[0021]FIG. 9 is an explanatory drawing showing a way of inspectingpressure losses in the heat exchanger,

[0022]FIG. 10 is a perspective view of the conventional heat exchanger;

[0023]FIG. 11A to FIG. 11C are drawings showing principal members of theconventional heat exchanger, and

[0024]FIG. 12 is results of the comparison between the examples of theinvention and comparative examples, shown as Table 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Referring now to the drawings, an embodiment of the inventionwill be described in detail. The same parts having the same function aredesignated by the same reference numerals and are not explained againthroughout The drawings showing the embodiments of the invention.

[0026] One of the objects of the invention is to provide a heatexchanger that is easy to manufacture and resistant to fluid leakagewith low fluid pressure losses.

[0027] A heat exchanger of the invention comprises: a corrugated plate;a base plate joined on one of surfaces of said corrugated plate; a coverplate joined on other surface of said corrugated plate; two types offluid flow paths A and B defined by said corrugated plate, said baseplate, and said cover plate along a longitudinal direction of saidcorrugated plate, said two types of fluid flow paths comprising aplurality of flow paths A defined by said one of surfaces of saidcorrugated plate and said base plate, and said plurality of flow paths Bdefied by other surface of said corrugated plate and said cover plate,said plurality of flow pats A and said plurality of flow paths B beingformed separately from each other,

[0028] one of upper end portions and lower end portions of saidcorrugated plate for forming the flow paths A, which are hermeticallysealed by providing two corresponding slant surfaces, and other one ofthe upper end portions and lower end portions of said corrugated platefor forming the flow paths B, which are hermetically sealed by providingtwo corresponding slant surfaces;

[0029] inlet ports for said fluid B being provided on one end portion ofthe corrugated plate which is the hermetically sealed side of the flowpaths A, and inlet ports for said fluid A being provided on other endportion of the corrugated plate which is the hermetically sealed side ofthe flow paths B;

[0030] outlet ports for said fluid A and for said fluid B respectivelybeing provided on opposite sides of said inlet ports for fluid A andfluid B,

[0031] wherein heat is exchanged between fluid A and fluid B via thecorrugated plate by supplying fluid A into the plurality of said flowpaths A and supplying fluid B into the plurality of said flow paths Brespectively from said inlet ports thus constructed toward said outletports.

[0032] In addition, in a heat exchanger of the invention, said coverplate and/or said base plate are hermetically sealed with the endportions of said corrugated plate by making cuts at the end portions ofthe corrugated plate to leave margins so as to be capable of brazingeither on said cover plate or on said base plate, and brazing saidmargins. In a heat exchanger of the invention, said corrugated plate isbrazed to said base plate and/or said cover plate by the brazingmaterial in a clad corrugated plate, and said flow paths A is completelydivided off said flow paths B.

[0033] Furthermore, in a heat exchanger of the invention, saidcorrugated plate comprises a cladding plate including a core materialand a brazing material formed on one side or both sides of said corematerial.

[0034] (First Embodiment)

[0035] Referring now to a perspective view shown in FIG. 1, a heatexchanger according to the first embodiment of the invention will bedescribed. A cladding plate with brazing material formed on bothsurfaces of the core material is used as a material of the corrugatedplate. A plurality of flow paths 3(A) are formed by joining a base plate2 on one of the surfaces of the corrugated plate 1. A plurality of flowpaths 6(B) are formed by joining a body portion 5 of the cover plate 4on the other surface of the corrugated plate 1. The base plate 2 and thesleeve portion 7 of the cover plate 4 are joined, and outlet ports 8 forfluid A are formed on the upper portion of the base plate 2, and outletports 9 for fluid B are formed at the lower portion of the body portion5 of the cover plate,

[0036] The openings at the lower end portion surrounded by the baseplate 2 and the cover plate 4 are inlet ports 28 for fluid A, and theinlet ports 28 are provided with hollow bodies (not shown) extending inthe same direction as the length of to respective flow paths 3, 6 forsupplying fluid A. The openings at the upper end are inlet ports 29 forfluid B, and the inlet ports 29 are provided with hollow bodies (notshown) extending in the same direction as the length of the respectiveflow paths 3, 6 for supplying fluid B.

[0037] At the upper end portions of the flow paths 3(A) and the lowerend portions of the flow paths 6(B), the end portions 10 of thecorrugated plate are bent so as to be brought into contact with eachother at the extremities thereof and processed into the shape of gableroofs. The minute gaps at the extremities 11 of the gable roofs arebrazed and hermetically sealed by filling brazing material, The lowerend portions of the flow paths 6(B), although they are not shown in FIG.1, are brazed and hermetically sealed by the same method as that for theupper end portions of the flow paths 3. The corrugated plate 1 and thebase plate 2, and the corrugated plate 1 and the cover plate 4 arejoined by the use of adhesive agent or sealing material, so that noleakage of fluid may occur between the flow paths 3(A) and the flow pats6(B).

[0038] In this embodiment, the reason why cladding material is used forthe corrugated plate 1 is to hermetically seal the flow paths 3(A) andflow paths 6(B) by brazing. At the end portions 10 of the corrugatedplate, the extremities 11 are bent toward each other and brought closer,and filled with brazing material in the minute gap therebetween so as tobe brazed and hermetically sealed. The reason is to facilitaterealization of the hermeticity at the end portions 10 of the corrugatedplate, and to alleviate the extent of turbulent flow in the vicinity ofthe fluid inlet ports 28, 29. The corrugated plate and the base plate,and the corrugated plate and the cover plate are joined by the use ofadhesive agent or sealing material, so that no leakage of fluid occursbetween the flow paths 3(A) and the flow paths 6(B). In other words, inthis embodiment, the end portions of the corrugated plate area brazed,and the corrugated plate and the base plate, and the corrugated plateand the cover plate are joined by the use of adhesive agent or sealingmaterial.

[0039] Referring now to FIGS. 2A to 2C, the way to hermetically seal theextremities 11 of the end portions 10 of the corrugated plate will bedescribed. A prescribed length of cut 13 is made along each crease 12 onthe end portion 10 of the corrugated plate to form a strip 14, a strip15, and a strip 16. The strip 14 and he strip 16, which are opposed eachother, are bent from the ends of the cuts 13 so that the extremities 11of the respective strips are brought closer with each other and formedinto the shape of a gable roof by the use of a prescribed metal die (notshown). The extremities 11 of the strip 14 and the strip 16, which arebrought closer, are brazed and hermetically sealed with brazingmaterial.

[0040] The angle α17 between the strip 14 and the strip 16 formed in theshape of a gable roof shown in FIG. 2C is preferably not less than 30degrees and not more than 120 degrees. The reason is that when it isless than 30 degrees, inclination becomes sharp and thus the roofportion becomes high, which results in increased restrictions in designchoice. When it exceeds 120 degrees, the effect of alleviating theturbulent flow cannot be obtained sufficiently.

[0041] In FIG. 3, the tip 14 and the strip 16 are bent in the vicinityof the respective extremities 11 and the surfaces of the bentextremities are formed to come into contact with each other. Thisexample shows the case where the surfaces of the extremities bent andbrought into contact with each other are formed to be in parallel withthe flow paths, which has lower resistance with respect to fluid. As inthis example, making surface joint at the contact portions 27 mayincrease hermeticity.

[0042] Furthermore, a heat exchanger of the invention comprises: acorrugated plate; a base plate joined on one of surfaces of saidcorrugated plate; a cover plate joined on other surface of saidcorrugated plate;

[0043] two types of fluid flow pats A and B defined by said corrugatedplate, said base plate, and said cover plate along a longitudinaldirection of said corrugated pit, said two types of flow pathscomprising a plurality of flow paths A defined by said one of surfacesof said corrugated plate and said base plate, and said plurality of flowpaths B defied by other surface of said corrugated plate and said coverplate, said plurality of flow paths A and said plurality of flow paths Bbeing formed separately from each other;

[0044] upper end portion and lower end portion of said corrugated plateforming the flow paths A or B, which are hermetically sealed byproviding two corresponding slant surfaces;

[0045] inlet ports provided on said base plate or said cover plateforming said flow paths A or said flow paths B, upper end portions andlower end portions of which are hermetically sealed, and outlet portsprovided opposite side of said inlet ports;

[0046] inlet ports provided on one end of said flow paths A or said flowpaths B, upper end potions and lower end portions of which are nothermetically sealed, and outlet ports provided on opposite side of saidinlet ports,

[0047] wherein heat is exchanged between fluid A and fluid B via thecorrugated plate by supplying fluid A into the plurality of said flowpats A and supplying fluid B into the plurality of said flow paths Brespectively from said inlet ports thus constructed toward said outletports.

[0048] (Second Embodiment)

[0049] Referring now to a perspective view of FIG. 4, the heat exchangeraccording to the second embodiment of the invention will be described.The shape of the end portions of the corrugated plate described inconjunction with the heat exchanger according to the first embodimentreferring to FIGS. 2A to 2C and 3 may be applied to this embodiment.

[0050] In the heat exchanger according to the second embodiment of theinvention, outlet ports 8 and inlet ports 28 for fluid A are provided onthe base plate 2 to supply fluid A through the flow pats 3(A), and fluid1 is supplied from the inlet ports 29 at the lower end portions of theflow paths 6(B) toward the outlet ports 9 at the upper end. In this heatexchanger, a cladding plate with brazing material formed on one of thesurfaces of the core material is used as material for the corrugatedplate.

[0051] Both end portions 10 of the corrugated plate 1 constituting theflow paths 3(A) are bent at the extremities thereof so that they arebrought into contact with each other into the shape of a gable roof. Theminute gaps at the extremities 11 of the gable roof are brazed andhermetically sealed by being filled with brazing material. In this case,brazing material is filled inside the gable roof.

[0052] In this heat exchanger, sealing work at both end portions of thecorrugated plate that constitutes the flow paths 3(A) can easily beperformed, and in addition, good fish can be expected and pressurelosses of fluid 6(B) can be reduced. The corrugated plate 1 and the baseplate 2 are joined by the use of adhesive agent or sealing material sothat no leakage of fluid occurs between the flow paths 3(A) and the flowpaths 6(B). Since attachment of the cover plate does not effect directlyon leakage of fluid between the flow paths 3(A) and the flow paths 6(B),any way of attachment can be employed.

[0053] Furthermore, a heat exchanger of the invention comprises: acorrugated plate; a base plate joined on one of surfaces of saidcorrugated plate; a cover plate joined on other surface of saidcorrugated plate;

[0054] two types of fluid flow paths A and B defined by said corrugatedplate, said base plate, and said cover plate along a longitudinaldirection of said corrugated plate, said two types of fluid flow pathscomprising a plurality of flow paths A defied by said one of surfaces ofsaid corrugated plate and said base plate, and said plurality of flowpaths B defied by other surface of said corrugated plate and said coverplate, said plurality of flow paths A and said plurality of flow paths Bbeing formed separately from each other;

[0055] one end portion of the upper end portion or the lower end portionof said corrugated plate forming the flow path A and other end portionof the upper end portion or the lower end portion of said corrugatedplate forming the flow path B, which are hermetically sealed byproviding two corresponding slant surfaces, respectively;

[0056] outlet ports for said fluid B being provided on one end portionof the corrugated plate which is the hermetically sealed side of theflow paths A, and outlet ports for said fluid A being provided on theother end portion of the corrugated plate which is the hermeticallysealed side of the flow paths B;

[0057] inlet ports for said fluid A or inlet ports for said fluid Bbeing provided on said base plate or said cover plate forming said flowpaths A and said flow paths B,

[0058] wherein heat is exchanged between fluid A and fluid B via thecorrugated plate by supplying fluid A into the plurality of said flowpaths A and supplying fluid B into the plurality of said flow paths Brespectively from thus constructed said inlet ports toward said outletports.

[0059] (Third Embodiment)

[0060] The shape described in conjunction with the first embodimentreferring to FIG. 1 is applied to the heat exchanger according to thethird embodiment of the invention. As regards the end portion of thecorrugated plate, the shape described in conjunction with the embodimentreferring to FIGS. 2A to 2C and FIG. 3 can also be applied.

[0061] In the heat exchanger in this embodiment, a cladding plate withbrazing material formed on the both surfaces thereof is used as materialfor corrugated plate. The corrugated plate 1 and the base plate 2, andthe corrugated plate 1 and the cover plate 4 are joined by brazing withbrazing material formed in the corrugated plate. In other words, brazingmaterial that is melted at the time of heating is filled in minute gapsformed between the corrugated plate 2 and the base plate 2 and betweenthe corrugated plate 1 and the cover plate 4, and then cured aftercooling down, so that the gap is hermetically sealed. In other words, inthis embodiment, brazing at the end portions of the corrugated plate andbrazing between the corrugated plate and the base plate, and between thecorrugated plate and the cover plate are performed simultaneously.According to this embodiment, hermeticity is increased.

[0062] (Fourth Embodiment)

[0063] The shape described in conjunction with the second embodimentreferring to FIG. 4 can be applied to the heat exchanger of the fourthembodiment of the invention. As regards the end portion of thecorrugated plate, the shape described in conjunction with the secondembodiment referring to FIGS. 2A to 2C and FIG. 3 can also be applied.

[0064] This heat exchanger uses a cladding plate with brazing materialformed on one of the surfaces thereof as material of the corrugatedplate. The corrugated plate 1 and the base plate 2 are joined by brazingwit brazing material formed in the corrugated plate. In other words,brazing material that is melted at the time of heating is filled in aminute gap formed between the corrugated plate 1 and base plate 2, andthen cured after cooling down, so that the gap is hermetically sealed.Since attachment of the cover plate does not effect directly on leakageof fluid between the flow paths 3(A) and the flow paths 6(B), any way ofattachment can be employed. According to this embodiment, hermeticity isincreased.

[0065] According to the third embodiment and the fourth embodiment, itis not necessary to spend much time and efforts as in the case of usingadhesive agent or sealing material. Since the cladding plate is joinedby brazing with brazing material, the flow paths 3(A) and the flow paths6(B) can be divided off completely, and leakage of fluid between theflow paths 3(A) and the flow paths 6(B) can completely be avoided.

[0066] (Fifth Embodiment)

[0067] The shape described in conjunction with the first embodimentreferring to FIG. 1 can be applied to the heat exchanger of the fifthembodiment of the invention. In this embodiment, the corrugated plate inwhich the end portions thereof are formed into the roof shape and theextremities thereof are processed to be brought closer is employed.

[0068] Referring now to FIG. 5A to FIG. 5C, this embodiment of theinvention will be described. This heat exchanger uses a cladding platewith bring material formed on both surfaces thereof as material of thecorrugated plate. As a fist step, cuts 33 are made from the edges of theend portions of the corrugated plate on one side along the creases atthe comers defined by shorter sides 30 and the longer sides 31 inadvance.

[0069] Then, the opposed longer sides 31 are folded into the shape of aroof so that the extremities thereof are brought closer, andsimultaneously, the shorter sides 30 are bent and flattened out towardthe folded opposed longer sides 31 as if they enfold the bent opposedlonger sides 31. Preferably, as shown in FIG. 5C, they are flatteningout so that the end surfaces of the longer sides 31 and of the shortersides 30 are aligned and overlapped with each other, and that the bentcontact surfaces of the extremities of the longer sides 31 are formed tobe upright.

[0070] By shaping according to the above method, the end portions of thecorrugated plate 35 formed by the shorter sides 30 and the longer sides31 may be formed into substantially T-shape. The minute gap formedbetween the corrugated plate 1 and the base plate 2, and between thecorrugated plate 1 and the cover plate 4 may be hermetically sealed bythe use of adhesive agent or sealing material, or may be joined bybrazing using brazing material formed in the corrugated plate.

[0071] (Sixth Embodiment)

[0072] The shape described in conjunction with the second embodimentreferring to FIG. 4 may be applied to the heat exchanger according tothe sixth embodiment of the invention. The shape described inconjunction with the fifth embodiment referring to FIGS. 5A to 5C may beapplied as a method of forming the end portions of the corrugated plateinto the roof shape to bring the extremities closer.

[0073] In the cases of the fifth embodiment and of the sixth embodimentdescribed in conjunction with FIG. 1, no cut is made on the end formedinto a substantially T-shape, but it is continuous. Therefore, there isno probability leaving a hole after brazing along the cut, therebyensuring hermeticity. Since a special metal die is used for processing,working procedure can be facilitated significantly in comparison withthe case where adhesive agent or sealing material is used.

[0074] (Seventh Embodiment)

[0075] The shape described in conjunction with the first embodiment isapplied to the heat exchanger according to the seventh embodiment of theinvention. In this embodiment, the corrugated plate having the endportions formed in the roof shape, and the extremities being broughtcloser and processed

[0076] Referring now to FIG. 6A to FIG. 6D, the embodiment of theinvention will be described. The heat exchanger uses a cladding platewith brazing material formed on both of the surfaces of the corematerial as material of the corrugated plate. As a fir step, cuts 43 aremade on the shorter sides 40 from the upper edges of the end portions ofthe corrugated plate on one side in advance. The cuts 43 are made on theshorter sides 40 so as to leave margins 44 not less than several mm inwidth on both sides closer to the longer sides 41. In other words, thecuts 43 are made so as to leave margins 44 for brazing the end portionsof the corrugated plate to the cover plate or to the base plate. Themargins 44 may have any width, for example, approximately 1 mm, as faras it can be used for brazing.

[0077] As a next step, the cuts 43 on the shorter sides 40 are expandedoutwardly, and then he expanded margins 44 are brought into contact withthe adjacent margins respectively so that the end surfaces of theextremities of the margins 44 are aligned and overlapped with eachother. The bent contact surfaces of the extremities of the margins 44are preferably formed to be upright.

[0078] After bringing the margins in contact, the extremities of theopposed longer sides 41 are brought closer into the roof shape, andsimultaneously, the shorter sides 42 are bent and flattened out towardthe folded opposed longer sides 41 as if they enfold the bent opposedlonger sides 41. As shown in FIG. 6D, they are flattened out so that theend surfaces of the longer sides 41 and of the shorter sides 42 arealigned and overlapped with each other. The bent contact surfaces of theextremities of the longer sides 41 are preferably formed to be upright.

[0079] By shaping according to the above method, the end portions 45 ofthe corrugated plate 45 formed by the shorter sides 40 and the longersides 41 may be formed into substantially T-shape. The minute gapsformed between the corrugated plate 1 and the base plate 2, and thecorrugated plate 1 and the cover plate 4 may be hermetically sealed bythe use of adhesive agent or sealing material, or may be joined bybrazing using brazing material in the corrugated plate.

[0080] (Eighth Embodiment)

[0081] The shape described in conjunction with the second embodimentreferring to FIG. 4 may be applied to the heat exchanger according tothe eighth embodiment of the invention. The shape described inconjunction with the seventh embodiment referring to FIGS. 6A to 6D maybe applied as a method of forming the end portions of the corrugatedplate into the roof shape to bring the extremities closer.

[0082] In the cases of the seventh embodiment and of the eightsembodiment, no cut is made on the end portions formed into asubstantially T-shape, but it is continuous. Therefore, there is noprobability of leaving a hole after brazing along the cut, therebyensuring hermeticity. Since a special metal die is used for processing,working procedure can be facilitated significantly in comparison withthe case where adhesive agent or sealing material is used.

[0083] Furthermore, in other embodiment of the heat exchanger of theinvention, the flow paths A and the flow paths B are alternatelydisposed along the lateral direction of the corrugated plate describedabove, and the extent of turbulent flow of fluid that is generated inthe vicinity of the inlet ports is alleviated by the shape of the endportions hermetically sealed by providing two corresponding slantsurfaces.

[0084] The aforementioned end portions sealed by providing twocorresponding slant surfaces are further sealed hermetically by brazing.The corrugated plate is formed of cladding material comprising corematerial and brazing material formed on both surfaces thereof and thecorrugated plate and the base plate, and the corrugated plate and thecover plate are respectively joined by brazing with brazing material ofthe corrugated plate.

[0085] The corrugated plate and the base plate, and the corrugated plateand the cover plate, which are brazed and joined, are further joined byadhesive agent or sealing material. The end portions hermetically sealedby providing two corresponding slant surfaces are provided with verticalsurfaces as margins for brazing, and hermetically sealed by brazing thevertical surfaces.

[0086] As is described thus far, the invention will produce its effectsby being applied to the given heat exchanger performing heat exchangevia the corrugated plate.

EXAMPLES Example 1

[0087] The invention will be described in detail referring to examples.A heat exchanger having a construction shown in FIG. 1 was manufactured.A corrugated plate 1 of cladding plate of 0.5 mm in thickness includingbrazing material of JIS4045 alloyed metal on both of the spices of thecore material of JIS3003 alloyed metal was used as a corrugated plate 1.

[0088] The end portions 10 which were to be the upper end portions ofthe flow paths 3(A) and the end portions which were to be the lower endportions of the flow paths 6(B) were processed to be brought closer intothe shape of a gable roof in advance by the method described inconjunction with FIGS. 2A to 2C, and joined by brazing by fillingbrazing material in the minute gaps at the extremities thereof in thesubsequent heating process. The corrugated plate 1 and the base plate 2,and the corrugated plate 1 and the body portion of the cover plate 5 arerespectively joined by adhesive agent.

Example 2

[0089] A heat exchanger having the same construction as the one shown inFIG. 1 other than that the corrupted plate 1 and the base plate 2, andthe corrugated plate 1 and the body portion of the cover plate 5 werebrazed by brazing material in the corrugated plate was manufactured.

Example 3

[0090] The heat exchanger having the same construction as the one shownin FIG. 1 other than that the shape of the end portion of the corrugatedplate is formed continuously without any cut into T-shape by the methodshown in FIGS. 6A to 6D was manufactured by the same method as that inExample 2.

First Comparative Example

[0091] A corrugated plate formed of JIS3003 alloyed metal plate of 0.5mm in thickness was used as a corrugated plate 1. The end portions 10which were to be upper end portions of the flow paths 3(A) and the endportions which were to be the lower end portions of the flow paths 6(B)were processed to be brought closer into the shape of a gable roof inadvance by the method described in conjunction with FIGS. 2A to 2C, andhermetically sealed by filling sealing material 23 in the minute gaps atthe extremities thereof. The corrugated plate 1 and the base plate 2,and the corrugated plate 1 and the body portion 5 of the cover platewere joined by adhesive agent. A heat exchanger having a constructionshown in FIG. 1 other than the points described above was manufactured.

Second Comparative Example

[0092] A heat exchanger having a construction shown in FIG. 1 other thanthat the upper end portions of the flow paths 3(A) and the lower endportions of the flow paths 6(B) were hermetically sealed by fillingrubber material 26 and sealing material 23 without being processed to beformed into the shape of a gable roof was manufactured by the samemethod as that in the first comparative example.

[0093] In FIG. 7A, a schematic plan view showing the upper end portionsof the flow paths A in the first embodiment is shown. In the samemanner, FIG. 7B shows the second embodiment, FIG. 7C shows the thirdembodiment, FIG. 7D shows the first comparative example, and FIG. 7Eshows the second comparative example.

[0094] In the first, second, and third examples of the invention, theextremity 11 of the end portions 10 of the corrugated plate formed intothe shape of a gable roof are joined and hermetically sealed by brazingmaterial 25. In the second and third examples of the invention, thecorrugated plate 1 and the base plate, and the corrugated plate 1 andthe cover plate 4 are joined respectively by brazing. In particular, inthe example 3, there is no cut made at the end portions, and thesubstantially T-shaped portion integrally formed into the roof shape wasformed in continuity.

[0095] On the other hand, in the first comparative example, theextremity 11 of the end portions 10 of the corrugated plate formed intothe shape of a gable roof were hermetically sealed with sealing material23. In the second comparative example, the upper end portions are notformed into the roof shape, but hermetically sealed as is with sealingmaterial 23, or with sealing material 23 and rubber material 26.

[0096] The respective heat exchangers manufactured in the first to thirdexamples of the invention and in the first and second comparativeexamples were inspected for their hermeticity of the hermetically sealedend portions of the corrugated plates. Those having good hermeticitywere inspected for the pressures loss. The method of measuring thehermeticity will be described referring to FIG. 8. In a first place, theinlet port for fluid A of the heat exchanger is hermetically sealed anda hose 18 is attached to the outlet port 8 for fluid A in thewater-tight state.

[0097] Then, the heat exchanger as soaked into the water, andhigh-pressure air was blown into the flow paths 3(A) trough the hose 18.Presence of generation of air bubbles 19 from the hermetically sealedend portions 10 of the corrugated plate in the vicinity of the outletport 8 for fluid A of the heat exchanger was observed. The sameinspection was made also for the flow paths 6(B).

[0098] Inspection was made for 200 each of heat exchangers, andevaluated as; very good hermeticity (⊚) when the number of heatexchangers generated air bubbles was zero, good hermeticity (◯) when thenumber was not more than 5, and no good hermeticity (X) when the numberwas six or more. The results are shown in Table 1 as FIG. 12.

[0099] Pressure losses were inspected by, as shown in FIG. 9, mountingair channels 20, 21 at the inlet ports and the outlet ports of fluid A,blowing wind through the air channel 21 mounted at the inlet ports by afan, and checking the difference of air pressure between the airchannels 20, 21 by means of a minute differential pressure gauge 22. Theresults were evaluated as; good (◯) when the differential pressure wasless than 50 Pa, and no good (X) when the value was not less than 50 Pa.The results are shown in Table 1 as FIG. 12. The productivities are alsomarked in Table 1.

[0100] As is clear from Table 1, in the goods of the invention from Nos.1 to 3, every end portions of the corrugated plates were hereticallysealed by brazing after the extremities thereof were brought closer toreduce the sealing areas. Therefore, the sealing work can be made easilyand little leakage of fluid was observed.

[0101] In particular, example No. 3 of the invention which has no cut atthe extremities of the corrugated plate and formed into a continuousT-shape was superior in hermeticity. Since the end portions of thecorrugated plate were formed into the shape of a gable roof, the extentof turbulent flow of fluid was alleviated and pressure losses werereduced. Examples No. 2 and No. 3 of the invention in which theextremities of the corrugated plate, and the corrugated plate and thebase plate are brazed simultaneously were superior in hermeticity andexcellent in productivity.

[0102] In contrast to it, in the comparative example of No. 1, theextremities of the corrugated plate were gabled, but the end portions ofthe corrugated plate were hermetically sealed by sealing material.Therefore, sealing work took much time and efforts, and the hermeticitywas low. Comparative example No. 2 in which the end portions of thecorrugated plate were not gabled and hermetically sealed by sealingmaterial was low in hermeticity and pressure losses were increasedbecause extreme turbulent flow of fluid was occurred in the vicinity ofthe fluid inlet port.

[0103] As is described thus far, the invention relates to a heatexchanger in which fluid A and fluid B are flown in the flow paths 3(A)and flow paths 6(B) formed via the corrugated plate respectively forexchanging heat between the fluid A and fluid B. In the invention, whenhermetically sealing the flow paths 3(A) and the flow paths 6(B) at theend portions of the corrugated plate, the extremities were broughtcloser by forming the end portions of the corrugated plate into theshape of a gabled roof for brazing, and the sealing work can beperformed easily and the good results of sealing may be achieved. Inaddition, the extent of turbulent flow of fluid in the vicinity of thefluid inlet ports is alleviated, and thus pressure losses of fluid isreduced thereby realizing miniaturization of the fan and saving ofelectricity expense. Therefore, industrially outstanding effects can beproduced.

What is claimed is:
 1. A heat exchanger comprising: a corrugated plate;a base plate; a cover plate; a plurality of flow paths A and a pluralityof flow paths B defined by said corrugated plate, said base plate andsaid cover plate disposed so as to interpose said corrugated platetherebetween; and said plurality of flow paths A and said plurality offlow paths B being alternately and adjacently arranged on both sides ofthe corrugated plate for exchanging heat between fluid A and fluid B viathe corrugated plate by supplying fluid A through a plurality of flowpaths A and fluid B through a plurality of flow paths B, wherein atleast one of end portions of the plurality of flow paths is hermeticallysealed by making partial cuts at the end portions of the corrugatedplate and/or folding a part of the end portions of the corrugated plate,bending opposing ends of the corrugated plate so as to form respectivelyinto a shape of a gable roof, bringing at least a part of the ends ofthe corrugated plate into contact with each other, and brazing portionsin contact, so that openings of one of the flow paths A and the flowpaths B are hermetically sealed for allowing only one of the fluids toflow in/out at each end of the corrugated plate.
 2. A heat exchangeraccording to claim 1, wherein said cover plate and/or said base plateare hermetically sealed with the end portions of said corrugated plateby making cuts at the end portions of the corrugated plate to leavemargins so as to be capable of brazing either on said cover plate or onsaid base plate, and brazing said margins.
 3. A heat exchanger accordingto claim 1 or 2, wherein said corrugated plate is brazed to said baseplate and/or said cover plate by the brazing material in a cladcorrugated plate, and said flow paths A is completely divided off saidflow paths B.
 4. A heat exchanger according to claim 3, wherein saidcorrugated plate comprises a cladding plate including a core materialand a brazing material formed on one side or both sides of said corematerial.
 5. A heat exchanger comprising: a corrugated plate; a baseplate joined on one of surfaces of said corrugated plate; a cover platejoined on other surface of said corrugated plate; two types of fluidflow paths A and B defined by said corrugated plate, said base plate,and said cover plate along a longitudinal direction of said corrugatedplate, said two types of fluid flow paths comprising a plurality of flowpaths A defined by said one of surfaces of said corrugated plate andsaid base plate, and said plurality of flow paths B defined by othersurface of said corrugated plate and said cover plate, said plurality offlow paths A and said plurality of flow paths B being formed separatelyfrom each other; one of upper end portions and lower end portions ofsaid corrugated plate for forming the flow paths A, which arehermetically sealed by providing two corresponding slant surfaces, andother one of the upper end portions and lower end portions of saidcorrugated plate for forming the flow paths B, which are hermeticallysealed by providing two corresponding slant surfaces; inlet ports forsaid fluid B being provided on one end portion of the corrugated platewhich is the hermetically sealed side of the flow paths A, and inletports for said fluid A being provided on other end portion of thecorrugated plate which is the hermetically sealed side of the flow pathsB; outlet ports for said fluid A and for said fluid B respectively beingprovided on opposite sides of said inlet ports for fluid A and fluid B,wherein heat is exchanged between fluid A and fluid B via the corrugatedplate by supplying fluid A into the plurality of said flow paths A andsupplying fluid B into the plurality of said flow paths B respectivelyfrom said inlet ports toward said outlet ports.
 6. A heat exchangeraccording to claim 5, wherein said flow paths A and said flow paths Bare alternately disposed along a lateral direction of said corrugatedplate, and an extent of turbulent flow of fluid that is generated invicinity of said inlet ports is alleviated by a shape of said endportions hermetically sealed by providing said two corresponding slantsurfaces.
 7. A heat exchanger comprising: a corrugated plate; a baseplate joined on one of surfaces of said corrugated plate; a cover platejoined on other surface of said corrugated plate; two types of fluidflow paths A and B defined by said corrugated plate, said base plate,and said cover plate along a longitudinal direction of said corrugatedplate, said two types of flow paths comprising a plurality of flow pathsA defined by said one of surfaces of said corrugated plate and said baseplate, and said plurality of flow paths B defined by other surface ofsaid corrugated plate and said cover plate, said plurality of flow pathsA and said plurality of flow paths B being formed separately from eachother; upper end portion and lower end portion of said corrugated plateforming the flow paths A or B, which are hermetically sealed byproviding two corresponding slant surfaces; inlet ports provided on saidbase plate or said cover plate forming said flow paths A or said flowpaths B, upper end portions and lower end portions of which arehermetically sealed, and outlet ports provided opposite side of saidinlet ports; inlet ports provided on one end of said flow paths A orsaid flow paths B, upper end portions and lower end portions of whichare not hermetically sealed, and outlet ports provided on opposite sideof said inlet ports, wherein heat is exchanged between fluid A and fluidB via the corrugated plate by supplying fluid A into the plurality ofsaid flow paths A and supplying fluid B into the plurality of said flowpaths B respectively from said inlet ports thus constructed toward saidoutlet ports.
 8. A heat exchanger according to claim 7, wherein saidfluid A and said fluid B flow opposite directions.
 9. A heat exchangercomprising: a corrugated plate; a base plate joined on one of surfacesof said corrugated plate; a cover plate joined on other surface of saidcorrugated plate; two types of fluid flow paths A and B defined by saidcorrugated plate, said base plate, and said cover plate along alongitudinal direction of said corrugated plate, said two types of fluidflow paths comprising a plurality of flow paths A defined by said one ofsurfaces of said corrugated plate and said base plate, and saidplurality of flow paths B defined by other surface of said corrugatedplate and said cover plate, said plurality of flow paths A and saidplurality of flow paths B being formed separately from each other; oneend portion of the upper end portion or the lower end portion of saidcorrugated plate forming the flow path A and other end portion of theupper end portion or the lower end portion of said corrugated plateforming the flow path B, which are hermetically sealed by providing twocorresponding slat surfaces, respectively; outlet ports for said fluid Bbeing provided on one end portion of the corrugated plate which is thehermetically sealed side of the flow paths A, and outlet ports for saidfluid A being provided on the other end portion of the corrugated platewhich is the hermetically scaled side of the flow paths B; inlet portsfor said fluid A or inlet ports for said fluid B being provided on saidbase plate or said cover plate forming said flow paths A and said flowpaths B, wherein heat is exchanged between fluid A and fluid B via thecorrugated plate by supplying fluid A into the plurality of said flowpaths A and supplying fluid B into the plurality of said flow paths Brespectively from thus constructed said inlet ports toward said outletports.
 10. A heat exchanger according to any one of claims 5 to 9,wherein the end portions with said two corresponding slant surfacesprovided are hermetically sealed by brazing.
 11. A heat exchangeraccording to claim 10, wherein said end portions hermetically sealed byproviding said two corresponding slant surfaces are provided withvertical surfaces as margins for brazing, and hermetically sealed bybrazing said vertical surfaces.
 12. A heat exchanger according to anyone of claims 5 to 9, wherein said corrugated plate is formed ofcladding material comprising a core material and brazing material formedon one or both surfaces of said core material, and said corrugated plateand said base plate, as well as/or said corrugated plate and said coverplate are respectively joined by brazing with said brazing material ofsaid corrugated plate.
 13. A heat exchanger according to claim 12,wherein said corrugated plate and said base plate, and said corrugatedplate and said cover plate, which are brazed and joined, are furtherjoined by adhesive agent or sealing material.
 14. A heat exchangeraccording to any one of claims 5 to 9, wherein said cover plate and/orsaid base plate are hermetically sealed with the end portions of saidcorrugated plate by making cuts at the end portions of the corrugatedplate to leave margins so as to be capable of brazing either with saidcover plate or with said base plate, and brazing said margins.
 15. Aheat exchanger according to claim 14, wherein said corrugated platecomprises a cladding material including a core material and brazingmaterial formed on one or both surfaces of said core material.
 16. Aheat exchanger according to claim 15, wherein said corrugated plateincludes margins for brazing.
 17. A heat exchanger according to claim16, wherein said corrugated plate and said base plate, and saidcorrugated plate and said cover plate, which are brazed and joined, arefurther joined by adhesive agent or sealing material.